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Microbiotes Pulmonaires des patients atteints de mucoviscidose : interactions avec Pseudomonas aeruginosa / Cystic fibrosis lung microbiota and interactions with Pseudomonas aeruginosaPagès, Laurence 05 July 2016 (has links)
Le microbiote pulmonaire complexe de patients atteints de mucoviscidose (MV) peut être modifié par des facteurs de l'hôte (état clinique), xénobiotiques (antibiothérapie, habitat) ainsi que bactériens (pathogènes, commensaux). Notre étude a porté sur ces facteurs bactériens et plus particulièrement sur l'effet de Pseudomonas aeruginosa sur la structuration des microbiotes MV. Le but de notre travail a été d'étudier la structure et la composition des microbiotes pulmonaires chez des patients MV en fonction de la présence ou non de P. aeruginosa, ainsi que l'effet de ces microbiotes sur ce pathogène. Différentes approches nous ont permis de mettre en évidence ces résultats : i) certains genres bactérien (Stenotrophomonas, Prevotella) contenus dans un microbiote particulier plus pauvre et moins diverse sont associés préférentiellement à la présence de P. aeruginosa, ii) aucune diminution de richesse et de diversité n'est observée en amont d'une primo-colonisation par P. aeruginosa mais celle-ci entraine ultérieurement une diminution de richesse du microbiote, iii) le microbiote MV in vitro s'appauvrit et diminue en diversité plus rapidement lors d'une colonisation par une souche ayant un phénotype de « primo-colonisation », iv) les souches de primo-colonisation sont plus virulentes que les souches issues de colonisation chronique, v) ces souches sécrètent des molécules appartenant à la famille des 4-hydroxy-2-heptylquinoline (HAQs) bactéricides vis-à-vis de S. aureus. Une meilleure compréhension de cette modulation des microbiotes MV par P. aeruginosa offriraient de nouvelles stratégies thérapeutiques afin notamment de contrer l'implantation de ce pathogène au niveau pulmonaire et de limiter le développement d'infections chroniques chez les patients MV / Cystic fibrosis microbiota could be modified by different factors such as host factor (clinical state), xenobiotic factor (antibiotic, environment) or bacterial factors (pathogen, commensal). Our study focused on bacterial factors and more particularly on the impact of Pseudomonas aeruginosa on the CF microbiota structure. The objectives were to study the structure and the composition of CF microbiota whether the presence or not of P. aeruginosa and the impact of the CF microbiota on this pathogen. Different experimentations were used to get results : i) bacterial genus (Stenotrophomonas, Prevotella) were preferentially associated with P. aeruginosa in a poor and no diverse microbiota, ii) no previous decrease of microbiota richness was observed when the initial P. aeruginosa pulmonary colonization took place but this event was associated with a later decrease of microbiota richness, iii) In vitro model of CF microbiota showed a more important richness and diversity decrease with early colonization strains, iv) early colonization strains were more virulent than chronic colonization strains, v) these strains secreted bactericid molecules toward Staaphylococcus aureus belonging to 4-hydroxy-2-heptylquinoline (HAQs). Improve our understanding on how P. aeruginosa could modulate CF microbiota could permit to find new therapeutic strategies to prevent the early colonization and then to limit the chronic infections in CF patients
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Mudança do uso da terra e tipo de solo são fatores determinantes de fungos e arqueas no bioma pampa / Land-use change and soil type are determinants of fungal and archaeal communities in pampa biomeLupatini, Manoeli 29 February 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Land-use change and soil type can have significant impact on microbial communities of soil.
The Pampa biome in recent decades has undergone severe changes in landscape due to landuse
change, mainly for the introduction of exotic tree plantation and croplands. Different landuse
in Pampa biome were evaluated to determine the effect on the structure of soil microbial
communities. Furthermore, due to the presence of various soil types present in this biome, we
investigated whether different soil type harbor different microbial communities. Soil samples
were collected at two sites with different land-uses (native grassland, native forest, exotic tree
plantation and cropland) and in a typical toposequence in Pampa biome formed by Paleudult,
Albaqualf and alluvial soils. The structure of soil microbial community (archaeal and fungal)
was evaluated by RISA and soil functional capabilities were measured by microbial biomass
carbon and metabolic quotient. We detected different patterns in fungal and archaeal
community driven by land-use change and soil type showing that both factors are significant
drivers of microbial community structure and activity. Acacia and Eucalyptus afforestation
presented the most dissimilar communities when compared with natural vegetation. Although
differences in the communities were detected, the soils tested shared most of the taxonomic
unities and only a proportion of the community suffers changes caused by human
interference. / A mudança do uso da terra e o tipo de solo podem exercer impactos significantes sobre a
comunidade microbiana do solo. O bioma Pampa Brasileiro, nas últimas décadas, tem sofrido
severas mudanças na paisagem devido à mudança no uso da terra, principalmente pela
introdução de plantações de árvores exóticas e pelos cultivos agrícolas. Diferentes usos do
solo no bioma Pampa foram avaliados para determinar o efeito sobre a estrutura das
comunidades microbianas do solo. Além disso, devido à presença de vários tipos de solo
presentes neste bioma, foi investigado se diferentes tipos de solos abrigam diferentes
comunidades microbianas. Amostras de solo foram coletadas em duas áreas com diferentes
usos do solo (pastagem nativa, mata nativa, plantações de árvores exóticas e cultivo agrícola)
e em uma topossequência típica no bioma Pampa formado por Argissolo, Planossolo e solos
aluviais. A estrutura das comunidades microbianas do solo (arqueas e fungos) foi avaliada por
RISA e capacidades funcionais do solo foram mensuradas através de carbono da biomassa
microbiana e quociente metabólico. Diferentes padrões foram detectados nas comunidades de
fungos e arqueas influenciados pela mudança no uso da terra e pelo tipo de solo, mostrando
que ambos são importantes fatores da estrutura e atividade da comunidade microbiana.
Florestamentos de acácia e eucalipto apresentaram as comunidades mais diferentes quando
comparados com a vegetação natural. Embora diferenças nas comunidades foram detectadas,
os diferentes usos e tipos de solos avaliados compartilham grande parte das unidades
taxonômicas e mostram que apenas uma parte da comunidade sofre alterações causadas pela
interferência humana.
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